On Wed, Aug 21, 2002 at 05:49:54PM -0700, David Brumley wrote:
> The changelog for libpcap 0.7.1 seems to indicate that pcap_compile is
> reentrant.
Where?
The changelog item for 0.6 for "pcap_compile" says:
Fixed bug that could cause subsequent "pcap_compile()"s to fail
erroneously after one compile failed.
but, as I remember the terms IBM used in OS/360 manuals ages ago, that's
"serially reusable", not "reentrant". (The bug was in the way it
interacted with the lexical analyzer.)
I.e., the changelog item doesn't say that it allows two
"pcap_compile()"s to run *at the same time*, it just says that it fixes
a bug where you couldn't necessarily run it successfully after having
previously called it with an illegal expression. (There was another bug
in the 0.6 series where using the "vlan" keyword in an expression
wouldn't cause problems with that expression but would cause problems
with subsequent expressions; that was fixed in 0.7.)
> I tested it on a RH 7.2 box (2.4.18-5 kernel,
> glibc-2.2.5-39) and found it segfaulting about half the time when
> using pthreads. Is this a known issue?
Well, we've never particularly committed to it being reentrant; it's
not, as it uses a pile of globals, but I guess we never really thought
about it one way or the other, so I guess it's "known" in the sense that
we didn't commit to it being reentrant, but not "known" in the sense
that its non-reentrance was actively on our minds.
> How much of libpcap isn't thread safe?
I don't know (I'd have to read the source; you might want to do so
also).
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